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Claude Code v2.1.277 ·

Gateway self-host config: per-upstream custom headers, and a new loopback guard on telemetry forwarding

Gateway config adds per-upstream custom headers and blocks loopback telemetry URLs unless explicitly allowed

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KindImprovementsin v2.1.277,
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Gateway config adds per-upstream custom headers and blocks loopback telemetry URLs unless explicitly allowed

What

Self-hosted gateway configuration now lets each upstream provider block (Bedrock, AnthropicAws, Vertex, Foundry) specify custom headers to send with its requests.

Separately, the gateway's telemetry forwarding setting (telemetry.forward_to.url) now rejects loopback addresses (URLs pointing back at the same machine, such as localhost) by default. To forward telemetry to a local sidecar collector, an operator must set the environment variable CLAUDE_GATEWAY_ALLOW_LOOPBACK.

Why

Custom headers give gateway operators finer control over requests to each upstream provider. The loopback guard prevents telemetry from being silently misconfigured to point at the gateway's own machine, while still allowing it deliberately via the new environment variable for legitimate local-collector setups.

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Since it was published

The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.

Confirmed since Anthropic's documentation has since written up headers, on overview. | **Beta** | Preview features used for gathering feedback and iterating on a less mature use case. Availability may be limited, including through sign-up requirements or waitlists, and may not be publicly announced. Features may change sig… build-with-claude/overview see the edit
Added since A small documentation edit on computer-use-tool touched a line naming headers after this was published. Existing `computer_20251124` integrations keep working on the models listed for it under [Earlier tool versions](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#earlier-tool-versions), and earlier tool versi… agents-and-tools/tool-use/computer-use-tool see the edit
How sure we are
Two sources agreeTwo things we can check say the same as this entry.
Anthropic's documentation agreesA small documentation edit on computer-use-tool touched a line naming headers after this was published.
Anthropic's release notes agreeImproved the Claude apps gateway's loopback error messages to name CLAUDE_GATEWAY_ALLOW_LOOPBACK

See this entry in the whole of v2.1.277 →